I'm really new to programming in general, and for my comp sci class we have to create a rectangle. The teacher wants two classes- one that creates the lines (using Line2D.Double) and extends JComponent, and the JComponent, which is the viewer class. I only drew one line in the Triangle class because I wanted to get the program up and running before fiddling around with the more specific details.
My problem is that the frame.add in the viewer class isn't working... there's an error "The method add(Component) in the type Container is not applicable for the arguments (Triangle)".
JComponent is the name of an existing class (javax.swing.JComponent) - you shouldn't use that as the name of one of your classes. Or -if you need to do that for the purposes of your assignment- you need to declare Triangle as "... extends javax.swing.JComponent".